Chloride Restriction & AKI
There is some non-clinical experimental data that suggests the high amounts of chloride in some commonly used fluids impairs renal function. Effects might include renal vasoconstriction and reduced urine output. The authors set out to see if there was a detectable clinical impact on critically ill patients.
Association between a chloride liberal vs chloride-restrictive intravenous fluid administration strategy and kidney injury in critically ill adults
Association between a chloride liberal vs chloride-restrictive intravenous fluid administration strategy and kidney injury in critically ill adults
What did they do?
Design: a ‘before and after’ cohort trial following a switch in the whole unit’s fluid
Control: Chloride-liberal fluids. Primarily 0.9% NaCl, Gelofusine, Human Albumin Solution 4%
Intervention: Chloride-restrictive fluids. Primarily Hartmann’s solution, Plasmalyte, Human Albumin Solution 20%.
Population: a single large (22 bed) ICU in Australia.
Primary Objectives: Baseline to peak creatinine rise, AKI as defined by RIFLE criteria
Secondary Objectives: Need for RRT, mortality, hospital stay, ICU stay
Control: Chloride-liberal fluids. Primarily 0.9% NaCl, Gelofusine, Human Albumin Solution 4%
Intervention: Chloride-restrictive fluids. Primarily Hartmann’s solution, Plasmalyte, Human Albumin Solution 20%.
Population: a single large (22 bed) ICU in Australia.
Primary Objectives: Baseline to peak creatinine rise, AKI as defined by RIFLE criteria
Secondary Objectives: Need for RRT, mortality, hospital stay, ICU stay
What did they find?
Numbers: 760 patients in the control period, 773 patients in the intervention period. 100 patients from each arm included in ‘nested cohort’ with greater examination.
Results : Intervention group had a lower rise in their creatinine levels compared to the control group at 14.8 micromol/L, (95% CI 9.8 – 19.9 micromol/L) compared with 22.6 micromol/L (95% CI 17.5 – 27.7 micromol/L).
Decrease in AKI as defined by the RIFLE criteria but this was only significant for the ‘injury’ classification level at 3% (1.8 – 4.2) compared to 6.3% (4.5 – 8.1) of patients in the control group (p = 0.002).
A decrease in the use of RRT in the intervention group at 6.3% (4.6 – 8.1%) compared with 10% (8.1-12% in the control group (p = 0.005).
Analysis of the predetermined patient characteristics are not notably different between the groups with very similar markers of baselines co-morbidity and acute illness severity.
Calculate chloride administration dropped from a mean of 694 to 496 mmol/patient and sodium administration dropped from 750 to 623 mmol/patient with change in fluids
Results : Intervention group had a lower rise in their creatinine levels compared to the control group at 14.8 micromol/L, (95% CI 9.8 – 19.9 micromol/L) compared with 22.6 micromol/L (95% CI 17.5 – 27.7 micromol/L).
Decrease in AKI as defined by the RIFLE criteria but this was only significant for the ‘injury’ classification level at 3% (1.8 – 4.2) compared to 6.3% (4.5 – 8.1) of patients in the control group (p = 0.002).
A decrease in the use of RRT in the intervention group at 6.3% (4.6 – 8.1%) compared with 10% (8.1-12% in the control group (p = 0.005).
Analysis of the predetermined patient characteristics are not notably different between the groups with very similar markers of baselines co-morbidity and acute illness severity.
Calculate chloride administration dropped from a mean of 694 to 496 mmol/patient and sodium administration dropped from 750 to 623 mmol/patient with change in fluids
Is it any good?
Overall: Average.
Strengths: Decent numbers of patients. Results probably clinically significant as well as statistically. Pragmatic study design.
Weaknesses: Multiple areas for potential confounding; Unblinded, educational interventions which are unstated, changes in multiple fluids simultaneously e.g. reduction in gelatins used. Apparent higher fluid volumes given to intervention cohort (based on nested cohort numbers).
Strengths: Decent numbers of patients. Results probably clinically significant as well as statistically. Pragmatic study design.
Weaknesses: Multiple areas for potential confounding; Unblinded, educational interventions which are unstated, changes in multiple fluids simultaneously e.g. reduction in gelatins used. Apparent higher fluid volumes given to intervention cohort (based on nested cohort numbers).
Final Thoughts
Some big areas for potential bias but some useful information if the results are interpreted cautiously.
It’s probably best to minimise the amount of chloride we give our patients, unless there is a clear indication otherwise.
There are probably other interventions that are more important in minimising the impact of AKI on our patients than chloride load
It’s probably best to minimise the amount of chloride we give our patients, unless there is a clear indication otherwise.
There are probably other interventions that are more important in minimising the impact of AKI on our patients than chloride load
Written: Tom Heaton
Reviewed: Not done
3rd March 2016
Reviewed: Not done
3rd March 2016
References
- Yunos NM et al. Association between a chloride liberal vs chloride-restrictive intravenous fluid administration strategy and kidney injury in critically ill adults. JAMA. 2012. 308 (15). 1566-72.